A rotary printing unit has a plurality of rotatable printing cylinders. An offset printing unit, for example, has a plate cylinder and a blanket cylinder. The plate cylinder and the blanket cylinder are supported at their opposite ends in the frame of the printing unit. The ends of the cylinders are supported for rotation in the frame by respective bearing assemblies. The plate cylinder carries a printing plate having a surface on which an inked image is defined. The blanket cylinder carries a printing blanket. When the cylinders rotate in the printing unit, the plate on the plate cylinder transfers the inked image to the blanket on the blanket cylinder at a nip between the plate cylinder and the blanket cylinder. The blanket on the blanket cylinder subsequently transfers the inked image to the material being printed, such as a web of paper.
The printing plate and/or the printing blanket can be formed as a tube which is mounted on the respective cylinder by sliding the tube telescopically over the cylinder. When such a tubular printing member is to be moved telescopically over a cylinder, the cylinders are first moved into thrown-off positions in which they are spaced from each other across the nip. An opening must be provided in the adjacent side wall of the frame so that the tubular printing member can be moved longitudinally past the side wall of the frame through the opening. A clearance must also be provided for the tubular printing member to move past the bearing which supports the end of the cylinder on the adjacent side wall of the frame.